Good usability is vital to the success of any web site. This site has downloadable sets of web evaluation tools to assist in analysis of a web page based on numerous usability guidelines. Registration is required (free). http://zing.ncsl.nist.gov/WebTools/
Lane Becker writes, "Rather than a validation done once before completing a product... internal, qualitative usability testing [should be] done earlier, more frequently, and as part of the design process - not separate from it." http://www.adaptivepath.com/publications/essays/archives/000328.php
International Journal of Human-Computer Studies. Special issue of WWW Usability arising from a symposium entitled "The Missing Link: Hypermedia Usability Research and The Web". http://ijhcs.open.ac.uk/